Granular-type insulating materials used in providing thermal insulation are well known. Typically, conventional granular insulating materials consist of expanded or foamed light-weight polymers, such as polystyrene. The polymers are formed into approximately spherical granules which have an average diameter of about 1.5 millimeters.
It is known to use conventional polystyrene granules in construction where, for example, the granules are used as thermal insulation which is blown loose into attics or cavities, or are compacted together to form aggregate panels which range in thickness between 0.5 and 6 inches. While expanded polystyrene has low thermal conductivity and provides good thermal insulation, the low density of polystyrene makes conventional granules very poorly suited to absorb sound energy and substantially transparent to sound energy.
In another construction use, polystyrene granules are admixed with cement to produce a light-weight concrete slurry. In addition to producing set concrete having enhanced thermal resistance, the lighter weight of the concrete mixture advantageously facilitates vertical pumping, as for example, is required in the erection of high-rise buildings. A disadvantage in using conventional polystyrene granules in concrete slurries exists, however, in that the granules have an overall density less than about half of that of water and which typically ranges from about 0.2 to 0.5 grams/cm.sup.3. As a result of their low density, the polystyrene granules tend to float in the slurry resulting in their uneven distribution in the set concrete.
A further disadvantage with conventional polystyrene insulating granules exists in that if the granules are exposed to a flame, the polystyrene will readily burn, producing noxious fumes and potentially hazardous bi-products on combustion.
Conventional granular insulating materials also suffer the disadvantage that they are highly susceptible to damage by rodents and insects. In particular, mice and rats may easily burrow through and nest in either loose blown granules or aggregate panels made from such granules.